It's the lighting! I feel like it's a bit difficult to photograph because I've yet to see accurate photos of the set from other people either. The mods are indeed a bit darker than the renders, but just a tiny bit. I would say the set overall is around 98% accurate, the orange and light alphas are pretty much spot on. The mods are a smidge darker and slightly more cooler toned as well, which I personally like better as it gives off a "crisp wintery forest" feeling lol.